4. World of Warcraft (PC, 2004) — $8.5 billion

This massively multiplayer online game lets you play out characters from Blizzard's Warcraft universe. It's the most lucrative online game ever and made Blizzard a household name and a billion-dollar company.

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3. Street Fighter II (Arcade/SNES/Genesis, 1991) — $10.6 billion

Capcom

This Capcom fighting game would go on to spawn a massive franchise, with "Street Fighter V" one of the most anticipated releases of 2016.

1. Space Invaders (Arcade/Atari 2600) — $13.9 billion

Taito's Space Invaders wasn't the first video game, but it became a global phenomenon. Urban legend says that it caused a coin shortage in Japan when it first launched. To this day, these little aliens are pop culture icons.